A second explosion rocked Austin, Texas, hours after an earlier blast, which was apparently caused by a package left on a porch, killed a teen and injured a woman.

The first blast, reported about 6:44 a.m., killed a male teenager and injured a woman in her 40s. The second explosion today injured another woman, with authorities evaluating whether a second person was also hurt, according to the Austin Police Department.

Investigators said earlier that first blast today may be connected to a March 2 blast in Austin because of the composition of the explosive device used. The police chief declined to discuss the construction of the explosive device or what specific elements make it look similar to the earlier one.

The explosion "is very similar to the incident that occurred in Austin back on March 2, and if you’ll remember, that incident also occurred in the morning hours when the victim, in that case, went out front and found a package on their front steps that exploded causing that individual’s death," police chief Brian Manley said at a news conference Monday.

The first explosion today occurred at a single-family house in the northeast section of the city and appears to have been caused by a package that had been placed on the porch of a home rather than delivered by a mail service, police said. Police believe the explosion happened after residents took the package inside to open it.

"What we understand at this point is that earlier this morning, residents went out front, and there was a package on the front doorstep. They brought that package inside the residence and as they opened that package, both victims were in the kitchen and the package exploded causing the injuries that resulted in the young man’s death and the injuries to the adult female," Manley said today.

Authorities have warned residents that if they receive a package they are not expecting, they should contact the Austin Police Department.

The FBI told ABC News that it was responding to the first reported explosion and assisting Austin police, who are the lead agency handling the situation.

The Bureau of Alcohol, Tobacco, Firearms and Explosives has sent staff from both its national response team and reinforcements to bolster local field resources. The national response team is the entity that goes in to major incidents to investigate complex fires and explosions – most recently the church fires in the south and the Oakland warehouse catastrophe.

An explosion earlier this monthToday's blasts follow the explosion on March 2, which police received a call about at 6:55 a.m. that day.

The victim in that explosion, Anthony Stephan House, died from his injuries after being transported to a local hospital.

"That case was being investigated as a suspicious death," Manley said today. "It is now being reclassified and is now a homicide investigation as well. We are looking at these incidents as being related based on similarities that we have seen and the initial evidence that we have on hand here today compared to what we found on the scene of that explosion that took place a week back."

Manley noted that "we don't know the motive behind these" events though he said that all three of the homes involved in blasts today and on March 2 blast had African-American residents.

"We can not rule [out] that hate crime is at the core of this, but we’re not saying that’s the cause as well," he said.

Today's blasts come at a particularly busy time for Austin, as the city hosts the annual SXSW music, film and technology conference from March 13 until March 18.

ABC News' Gina Sunseri contributed to this report.

Austins a beautiful community, restaurants, country music, home of the UT, and Texas seat of government. Who would want to bomb it?

A second explosion rocked Austin, Texas, hours after an earlier blast, which was apparently caused by a package left on a porch, killed a teen and injured a woman.

The first blast, reported about 6:44 a.m., killed a male teenager and injured a woman in her 40s. The second explosion today injured another woman, with authorities evaluating whether a second person was also hurt, according to the Austin Police Department.

Investigators said earlier that first blast today may be connected to a March 2 blast in Austin because of the composition of the explosive device used. The police chief declined to discuss the construction of the explosive device or what specific elements make it look similar to the earlier one.

The explosion "is very similar to the incident that occurred in Austin back on March 2, and if you’ll remember, that incident also occurred in the morning hours when the victim, in that case, went out front and found a package on their front steps that exploded causing that individual’s death," police chief Brian Manley said at a news conference Monday.

The first explosion today occurred at a single-family house in the northeast section of the city and appears to have been caused by a package that had been placed on the porch of a home rather than delivered by a mail service, police said. Police believe the explosion happened after residents took the package inside to open it.

"What we understand at this point is that earlier this morning, residents went out front, and there was a package on the front doorstep. They brought that package inside the residence and as they opened that package, both victims were in the kitchen and the package exploded causing the injuries that resulted in the young man’s death and the injuries to the adult female," Manley said today.

Authorities have warned residents that if they receive a package they are not expecting, they should contact the Austin Police Department.

The FBI told ABC News that it was responding to the first reported explosion and assisting Austin police, who are the lead agency handling the situation.

The Bureau of Alcohol, Tobacco, Firearms and Explosives has sent staff from both its national response team and reinforcements to bolster local field resources. The national response team is the entity that goes in to major incidents to investigate complex fires and explosions – most recently the church fires in the south and the Oakland warehouse catastrophe.

An explosion earlier this monthToday's blasts follow the explosion on March 2, which police received a call about at 6:55 a.m. that day.

The victim in that explosion, Anthony Stephan House, died from his injuries after being transported to a local hospital.

"That case was being investigated as a suspicious death," Manley said today. "It is now being reclassified and is now a homicide investigation as well. We are looking at these incidents as being related based on similarities that we have seen and the initial evidence that we have on hand here today compared to what we found on the scene of that explosion that took place a week back."

Manley noted that "we don't know the motive behind these" events though he said that all three of the homes involved in blasts today and on March 2 blast had African-American residents.

"We can not rule [out] that hate crime is at the core of this, but we’re not saying that’s the cause as well," he said.

Today's blasts come at a particularly busy time for Austin, as the city hosts the annual SXSW music, film and technology conference from March 13 until March 18.

ABC News' Gina Sunseri contributed to this report.

Austins a beautiful community, restaurants, country music, home of the UT, and Texas seat of government. Who would want to bomb it?

They hate us cuz the ain't us.

I also read that all the victims were black, so there could be that angle.

_________________Disobedience is the true foundation of liberty. The obedient must be slaves.

Austins a beautiful community, restaurants, country music, home of the UT, and Texas seat of government. Who would want to bomb it?

They hate us cuz the ain't us.

Texas is a beautiful state. I'm particularly partial to the Austin area because it is a liberal zone. It's kind of like Tucson is to the State of Arizona: home of the university, making for a zone of liberal sanity amid all that otherwise (southern) anger and hostility.

Maddog wrote:I also read that all the victims were black, so there could be that angle.

Actually, three victims now. Third incident last night...only this time it was an Hispanic home. But it sounds like white supremacists from here. We'll see.

Yeah, be careful. These bombs could be anything. Any tips on a motive?

All of the targets and victims were POC, so I'm thinking racism.

The Austin police chief made an interesting/scary point today -- whoever's doing this is able to keep the bomb from detonating until someone handles it the way you'd handle an ordinary package. That suggests sophistication, and a colleague of mine suggested it might be somebody with military training.

Ben Mothafuckin' Reilly wrote:I really hope it works out that way. I think we need to apprehend the bomber or bombers and make sure we find out their motivation.

Actually, that's why I'm so glad the Florida high school shooter is still alive. Maybe we can learn something about why people do these things.

Interesting point on the shooter, but I think what is needed is people from both right and left to say no to extremism.

To me, at the moment, the message is about dividing people in the US, which is wrong and I have never seen the US, as divided. As I have read from history. I am not claiming its like that daily on the ground individuallly, but overall as a nation.

To me, what needs to happen is a message that brings people together. Not one that divides. All we see is pro-Trump and anti-Trump, which to me, misses the main issues. Trump uses issues to misdirect the American people. Where most of these issues are not even in the US. Like for example Sweden etc.

What people have to do, is show how trump is wrong and that America is united against hate and division. Not through violence or hate, but through unity. Not masked antifa thugs, but people reasoning their views to win people over against hate.

Sadly, all I am seeing is hate breeding hate from both sides

_________________Human beings are born with different capacities. If they are free, they are not equal. And if they are equal, they are not free.

Unfortunately, when the person in the WH is from a major crime family, running a global crime syndicate, using the government as a vehicle for his graft...well, it's polarizing on its own.

But this smells of southern white-supremacist, KKK, or down home racism. No claim of responsibility. No broader point. No message whatsoever. This is the way the KKK has always operated...just, ya know, burn the church and run.

Original Quill wrote:Unfortunately, when the person in the WH is from a major crime family, running a global crime syndicate, using the government as a vehicle for his graft...well, it's polarizing on its own.

But this smells of southern white-supremacist, KKK, or down home racism. No claim of responsibility. No broader point. No message whatsoever. This is the way the KKK has always operated...just, ya know, burn the church and run.

Then do you not have faith in your own justice system?

You see Quill, you are part of this problem.

Just like in Israel, they are preparing to take Benjamin Netanyahu on trial for crimes committed. It shows that no person should be above its laws.

I mean, I always understood America had a fair and just legal system

I mean how was Nixon taken down?

You want to combat the racism and this Far right terrorism in America?

Stop making this a war between the left and right. Starting bringing people together standing united against extremism from both quarters.

_________________Human beings are born with different capacities. If they are free, they are not equal. And if they are equal, they are not free.

Original Quill wrote:Unfortunately, when the person in the WH is from a major crime family, running a global crime syndicate, using the government as a vehicle for his graft...well, it's polarizing on its own.

But this smells of southern white-supremacist, KKK, or down home racism. No claim of responsibility. No broader point. No message whatsoever. This is the way the KKK has always operated...just, ya know, burn the church and run.

Then do you not have faith in your own justice system?

That's true. I no longer believe that the US is a nation of laws. We are proving everyday that politics trumps (no pun) law. It started with Dick Cheney getting let off by the snowflake Obama. He just made it worse. Now the cancer has metastasized, and look what appeasement has gotten us.

Didge wrote:I mean, I always understood America had a fair and just legal system

I mean how was Nixon taken down?

You want to combat the racism and this Far right terrorism in America?

Stop making this a war between the left and right. Starting bringing people together standing united against extremism from both quarters.

Didge, the cops don't join the robbers.

What do you have in mind? That we help the money launderers of the Russian mafia? That we just accept that 13-year old girls are being shipped and sold around the world for prostitution? This is how Trump is making his money. We give into Trump, and there is no law and order.

That's true. I no longer believe that the US is a nation of laws. We are proving everyday that politics trumps (no pun) law. It started with Dick Cheney getting let off by the snowflake Obama. He just made it worse. Now the cancer has metastasized, and look what appeasement has gotten us.

Didge wrote:So basically you are basing this off one situation?Even though many people are convicted everyday?I warned you about appeasement with Syria and inaction and look where we are now with Russia?You kept claiming the bollocks about baby killing and yet far more babies have been killed by your stance there

Didge, the cops don't join the robbers.

What do you have in mind? That we help the money launderers of the Russian mafia? That we just accept that 13-year old girls are being shipped and sold around the world for prostitution? This is how Trump is making his money. We give into Trump, and there is no law and order.

That we actually sanction and bar there people from doing buisness. The individuals. It has to take the world to deny them and stop them entering many countries. You should never punish a country based off these criminals.

I fail to see how you fight Trump with the above accusations?People are never going to believe that, when you have an already highly skeptical nation.What you must do, is tackle him on policies. Unless you have evidence on claimed crimes of course. To bring someone down, has to be done on their policies, when they are President. Its no good trying to deligitimize them. The recent case where Corbyn was actually known to visit a commie spy, shows people do not care. They do care what will effect them. This story would have effected them in the Cold war but not now. Mainly as people are not living this. Hence why Corby did not suffer this. Where Corbyn falls down, is like yesterday. He teried to score political points off Russia, when he is clearly in their pocket on their propagande TV channel. He shot himself in the foot with that. Hence why you have to allow Trump to do the same, unless you have evidence to convict him.

Trump is ensuring that the Republicans, will not have a hope of having a majority for the next couple of decades

_________________Human beings are born with different capacities. If they are free, they are not equal. And if they are equal, they are not free.

It's a very common theme discussed here in America. It was anticipated before he took office, seen right away as he took office, and all the criticisms have been vindicated. He has no plan, no perspective, nor any ideology.

Ben Mothafuckin' Reilly wrote:I really hope it works out that way. I think we need to apprehend the bomber or bombers and make sure we find out their motivation.

Actually, that's why I'm so glad the Florida high school shooter is still alive. Maybe we can learn something about why people do these things.

Interesting point on the shooter, but I think what is needed is people from both right and left to say no to extremism.

To me, at the moment, the message is about dividing people in the US, which is wrong and I have never seen the US, as divided. As I have read from history. I am not claiming its like that daily on the ground individuallly, but overall as a nation.

To me, what needs to happen is a message that brings people together. Not one that divides. All we see is pro-Trump and anti-Trump, which to me, misses the main issues. Trump uses issues to misdirect the American people. Where most of these issues are not even in the US. Like for example Sweden etc.

What people have to do, is show how trump is wrong and that America is united against hate and division. Not through violence or hate, but through unity. Not masked antifa thugs, but people reasoning their views to win people over against hate.

Sadly, all I am seeing is hate breeding hate from both sides

A lot of folks make a good living keeping the hate alive. It's not uncommon for folks to attack their own, in an attempt to blame others.

_________________Disobedience is the true foundation of liberty. The obedient must be slaves.

It is not known if the blast is related to three package bombs that have killed two and injured two in the Texas capital.

Two people have been injured in another explosion in Texas’ capital, after three package bombs detonated earlier this month in other areas of the city and killed two people and injured two others.

Austin-Travis County Emergency Management Services reported that an explosion in southwest Austin injured two men in their 20s who were hospitalized with injuries that didn’t appear to be life-threatening.

There was no immediate word on what caused the blast or if it was related to the previous ones. Those blasts began when a package bomb exploded at an east Austin home on 2 March, killing a 39-year-old man.

Austin police issue alert after spate of package bombs leaves two dead Read moreTwo more package bombs then exploded on 12 March, killing a 17-year-old, wounding his mother and injuring a 75-year-old woman.

Sunday’s explosion occurred far from the first three blasts, which happened in separate, suburban neighbourhoods in the eastern part of the city.

Police blocked entrances to the neighbourhood where the explosion occurred and put up yellow tape about half a mile from the home where it happened. They urged those living nearby to stay in their homes.

Despite that order, neighbours milled around just outside the tape, but they said they hadn’t seen or heard much. FBI agents were conducting interviews with some of them.

The latest explosion came hours after authorities raised the reward by $50,000 for information leading to the arrest of whoever is responsible for the first three explosions. It now totals $115,000.

AUSTIN (KXAN) - The latest of four bombings in the Austin area in the past 16 days has a "higher level of sophistication" than the previous three, according to an update from Austin Interim Police Chief Brian Manley.

"We are clearly dealing with what we expect to be a serial bomber at this point," Manley said.

Hours after the bombing Manley said it is "very possible" the device in Sunday night's explosion was triggered by a trip wire. In a press conference around 10 a.m., he said the device that exploded has similarities to the other explosive devices, based on preliminary results, even though it does use a more complex tripwire system. He noted in an earlier press conference that the bombs have different kinds of projectiles within them.

Two men, who are 22 and 23 years old respectively, were either riding or pushing their bicycles, when the latest bomb next to a fence exploded in the "Travis Country East" subdivision in southwest Austin around 8:32 p.m. Both men are in good condition at the hospital, according to a spokesperson for St. David's South Austin Medical Center, but do have significant injuries. The Austin Police Department confirmed both men injured in the latest bombing are white, while the other victims were black or Hispanic.

APD initially asked homeowners within a half-mile radius of the intersection of Dawn Song Drive at Republic of Texas Boulevard to stay inside their homes until 10 a.m. Monday, but extended that time to 2 p.m. Republic of Texas Boulevard is blocked between Missions Oaks and Travis Country Boulevard.

Because of the concern about the latest bomb possibly having a tripwire device -- in which a victim puts pressure on a wire or fishing line to detonate it -- officials waited until it was daylight to sweep the area and begin a thorough search and analysis of the blast. Along with more than 500 federal agents, bomb technicians from San Antonio and Houston are headed to Austin to help with the case.

Chief Manley said in a press conference at 1:45 a.m. Monday that the possibility the bomb was triggered by a trip wire and the fact that the explosive device was left next to the road instead of on a front porch like the previous three cases necessitated a new warning to the public:

"We now need the community to have an extra level of vigilance and pay attention to any suspicious device, whether it be a package, a bag, a backpack, anything that looks out of place. And do not approach it. Again do not approach items like that, but instead call 911 to report it so we can go out and make sure it’s safe."

Initial reports indicate some key differences between the latest bombing and the other three, including that it happened at night, did not occur in east Austin, did not appear to be on someone's front porch, may have been set off by a trip wire and may not be a package. Police are asking anyone who sees anything suspicious -- not just a package -- to call 911.

Police are also looking for any surveillance video from the area of the latest bombing. They ask Travis Country residence to call 512-974-5210 if they have any video of the blast, or suspicious people or vehicles in the area.

"This has to be a community response," Manley said Monday morning. "This is something we have to solve as a community."

The four bombingsSunday night's bombing took place just after 8:30 p.m. Austin-Travis County EMS says it originally responded to the 4700 block of Eagle Feather Dr., located off of Southwest Parkway and west of South MoPac Expressway. However, when they arrived, ATCEMS and Austin police said the explosion was actually in the 4800 block of Dawn Song Drive, which is one block away.

The explosion Sunday evening is the fourth such incident since March 2, when 39-year-old Anthony Stephan House was killed by a package bomb in northeast Austin. A second (east Austin) and third bombing (southeast Austin) during the morning hours of March 12 ended in another person being killed and another two injured.

"Three targeted attacks and now a random victim, we definitely see a change in the method the suspect is using," Manley said. He added that at this point officials are not willing to classify these bombings as domestic terrorism or hate crimes because they don't know enough, and don't want to cut themselves off from considering all possibilities just yet.

Sunday night's bombing came less than 12 hours after the Austin Police Department held a news conference pleading for the person responsible for the recent bombings to come forward before anyone else was injured or killed.

"We want to understand what brought you to this point and we want to listen to you," said Chief Manley.

During the news conference, authorities also increased the reward amount to $115,000 for any information leading to the arrest of the suspect or suspects.

Neighborhood effectsAustin ISD said in a Facebook post that its school buses will be unable to go into the neighborhood Monday Any tardies or absences due to the situation will be excused, the district said. Two nearby schools -- St. Gabriel's Catholic School and St. Andrews's Episcopal School -- are on two-hour delays. Regents High School said it initially would have a delay to perform a security sweep, but later canceled classes entirely.

Neighbors Heard the BlastStan Malachowski was inside his home when he heard the noise, but didn't think anything of it initially.

"It was loud enough to hear inside of our house with our windows and door shut. Again, airplanes go by and cars backfire so we didn’t think much of it," says Malachowski.

Malachowski and his family were out of town last week for spring break, but they had been following the bombing news.

"It’s not just an east Austin thing, or north Austin thing, it’s now southwest Austin. This is not good," says Malachowski.